How would one find if the axle housing is bent? I have a leak at the driver side on the ford 9" in the rear. You can watch the caliper slide back and forth with the tire off indicating something is not lined up true.

I run moser 31 spline shafts and pulled it, rolled it on some steel tubing and could not see any wobble to indicate a bent shaft.

Next would have to be a bent housing. Is there a "TRICK" one can use to find out? Or would i have to pull the axle and take the housing somewhere?

If you pull everything out of the housing and shine a bright lite through it,It will have a perfectly round shadow,if it isn't bent ,iirc.I have never done it,but thats how they do it, I believe,and some times you can straighten them also.
google or maybe you tube.

As for the caliper moving, did you put some lug nuts back on to hold the rotor? Is the rotor warped? If the flange is bent, it won't necessary cause a leak but will cause a shimmy in the rear. Pulling the axle out and putting it back in without replacing the seal certainly won't help the leak.

A bent housing will not cause a rotational wobble. The housing is fixed. A bend housing can cause wheel bearings or even carrier bearings to go bad. I would replace the seal and not worry about it. I had a 44 that had a wobble for the longest time but on road I couldn't notice it.

I'm almost sure its just the flange that is bent. I think you can also true it up with a press.

Do you notice a soft brake pedal? This was the only thing I did notice, a slight soft first brake due to the caliper being pushed apart.

Yeah I put the lugs back on and put it in drive and let it spin on jackstands.

I only put it back in without changing the seal since the seal has to be pressed off and than on, i cannot do this and i'll live with the leak for now. Figured I'd find out why its like this before I change the seal and have that go bad in a few days.

Like said I do not know how long its been like this. It always has had a slight vibration in the seat so maybe this is why. I'll see if my neighbor can chuck it up on his lathe and see how bent the flange is. Than if its not to much see if he can true it up...or will that mess up the case hardening moser does? Or some say find the high spot and smack it with a BFH......

They do if you have original receipt. I have no clue where that is As for getting a stock shaft, I have no idea what this axle came from. Bill aka KillerB went through 3 sets from moser till he sent in my stock 28 spline shafts so they could match them up. And to think I went 31 spline for easy access to spares when I should of just went with 35 spline. Oh well .

When they measure shafts, do they measure from the outer edge of the flange where the rotor backing sits? Or at the back of the flange where the shaft begins?

I'm a retard....... so I took the rotor off and there was crap between the two mating surfaces...... cleaned it, bolted rotor back down and it was fine. So thank you all for the help! Now to just find a good seal to use......